{
  "bibcode": "2010GCN.10470....1T",
  "body": "E. Troja (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), S. Campana (INAF-OAB),\nJ. R. Cummings (NASA/UMBC), A. de Ugarte Postigo (INAF-OAB),\nP. A. Evans (U Leicester), J. M. Gelbord (PSU),\nO. Godet (U Leicester), C. Guidorzi (U Ferrara),\nS. T. Holland (CRESST/USRA/GSFC), H. A. Krimm (CRESST/GSFC/USRA),\nR. Margutti (Univ Bicocca&OAB), C. Pagani (U Leicester),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nB. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU) and\nR. L. C. Starling (U Leicester) report on behalf of the Swift Team:\n\nAt 09:05:38 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100305A (trigger=414905).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 168.365, +42.376 which is \n   RA(J2000) = 11h 13m 28s\n   Dec(J2000) = +42d 22' 34\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a total duration of about 20 sec, starting at ~T+50 \nrelative to the start of the image trigger interval.  The peak count rate\nwas ~500 counts/sec (15-350 keV), at ~65 sec after the trigger. \n\nThe XRT began observing the field at 09:07:57.6 UT, 139.2 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 168.36762, 42.40281 which\nis equivalent to:\n   RA(J2000)  = 11h 13m 28.23s\n   Dec(J2000) = +42d 24' 10.1\"\nwith an uncertainty of 4.4 arcseconds (radius, 90% containment). This\nlocation is 96 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at http://www.swift.ac.uk/sper.  We\ncannot determine whether the source is fading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of\n2.14e+20 cm^-2 (Kalberla et al. 2005). \n\nThe initial flux in the 2.5 s image was 4.86e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 122 seconds with the White filter\nstarting 144 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.01. \n\nBurst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/too.html.)",
  "circularId": 10470,
  "createdOn": 1267780925000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 100305A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 100305A"
}